Manufacture of inactive menthol



" Patented AugQ 9, L19V-:so

f i 1,173,506 if? 'A ier-Mii.A Lsor'rurirgiojer, for;nussnnnoio'nrexaesnn, ,Anjo exertion ksl'ri'zri'I-rJ forA DUSSEL- iesmerazeseeoes .To www"@mamme GESELL- v SCHAKFTMIT'-nEsCrIRAnKtrnn.,Iafiof'ruidy ort,DeUssELnoRF-QBERKASSEL, `ornnivmlvf MnunA'oru -oIlAoTIvn-.MENTOL fjN'q Drawing'. npplvication1ed-5Jeief2';1927; seriailn.`zo2,457,jand in. .Germany December zaiizs,

'The .present inventionzrefers.tof a new' metliod 'of manufacturingvvinactive mentliok' the racemate. of lnati'nal menthol, Vfrom itsisomers'. f 5- .Theprocess consistsfin heatingto temperatures .above100.k degrees' centigradethe said isomers of inactivementhol withmentholates of the `earth -alkal'inefmetalsr Suitablemen-` tholates 'ofthe earth' alkaline metals.1 are 10 those ofthecalci'um, barium,Istrontium,mag-

nesium, aluminium, Which mentholates have g notyetbeen described'.- -One`may use theqmenisomers;

. tholates derived rorn inactive menthol. onits` The mentholates usuableforprocess vmay be prepared either bythe" action of .the earthfalkalinemetal l (suitable `for .the I `A} reparationtofaluminium inefntholate)von inactivementholviaits isomers or by. the reacg 20 tion of'kina-ctivementhotviz. its gisomersvvth suitable compounds of the earth alkalinemetals,y for instancey earth ,alkalinejalcoho- ,lates'or earthy alkalineamides;` One may prepare the Y ,nientholates of f the earth, alkaline 25metals beforeth'eir Aaotionon the'` isomersof 'tholates andthen causethem to acton*.the isomers of theinactive menthol. Onev may A.transformedintothe latter. `It is'notneces-v vsary that themetalandthe'mentholsare used in a molecular proportion, one mayV use lessamounts of the earth l alkaline metalor metal y c ,compoundthannecessary tofbindiall menthol Vin theform--ota mentholate.The,isomers of he: inactivementhol toibe thol are for instancethehydrogenation products ofV thy-mol, yinactive lnenthone, (inactive1,625,771, ,dated EApril .19th, 19.27, and-ithaca;

pending applications. S-rial Number 83H3 ',led fJ une .26th,1926`ySerialyNu'ruben-113,8,834:

i 1;;*50 fledJ une 26th, Theisomers eontained the inactive menthol',-isolate the vsaid' menehowevery also form the A.menthe,lates oi irthe Yyearth alkaline metals in the ypresence,of suri plus',inaotivennenthol.or `Ainythe presenceqo .Y surplusisom'ers of the inactive menthol totreatedggfor the manufacture Vo.iflinactiveme'n-l thereinare firstlyinactive neomenthol, (melt-` ing `point 5cl-52 v.degrees centigrade,lboiling point 2l2pdegrees centigrade, at 760 mm. i Y Yp1'es'su`re,acidphthalatemelting point 177 de# ygrees centigrade, paranitrobenzoatemeltingp'o1nt79Y-f80 degreesv centigrade) secondly inactiveneoisomenthol (melting point :l2-14 degrees centigrad'e, boiling point214,5 de@ grees centigrade at 760-mm. pres'sure,.`aeid nphthalatemelting point'QO-QEZ degrees centimm1 Lpressure, acid`phthalate.. melting. point .6@ grade, paranitrobenzoate.,melting proint56 65kml 1139115 degrees centigrade;paranitrobenz atemelting. point 65`degrees cen"pigra-de)1.3"` seethe icopending Vapplication;Serial Numberl# 146,564 filed Novemberth, 1926. @j

t ,"One may "also,y luse .y mixtures ofy the isomers ofltheinactlvementhol.

tholg with mentholatesof learth 'alkaline met.-

.several ...Byheatingfthe isomers ofthe'inactlveinen;`-

ais one .obtains azmixture Y,contain-ing yinactivementhol.- whichlattermay bejseparated by ai ,freezing out process.v or a fractionaldistillaf` fr'om-.inactive menthol,may be mixedfwitli isomersfofinactive menthol obtained 'byany againtofthe 4present process, or maybeagi- Vvtion `orgbothg operations,f`'see U.; Si Patent@` A11,625,771dated {Api-i1' 19th,^i927,1m1 the.co.;- pending. applications :SerialNumberl 118,833 y iiled `June 26th, 1926,- Serial Number118,834r .Yfiled June 26th,7,1926. .',Tlie Vmixtures Kfreed, l j

tated if desired yafter admixture ofthymol;

inactive menthneor inactive isomenthoneor inactivepiperitone'"ori-mixtures.ofthem,'in Y f thepresence of hydrogenaitingjcatalystsland hydrogen under pressure?` whereby new V'amountsof inactivementhol'are formed---(fsee U. SQPailt ,"1 ,625,771 dated April19th,"l927 'aiidftheV copending applications "Serial Num# @rc1-:18,833filed une 26th and Serial. NumberllSll filedJuneQth','1926).'` l p'Example ,Ly-,11,00 ypartsfby Weight` -oli' inac- I n tivefneoisomentholv(melting,pointIQI-Mfdef` i greescentigrade) care mixed Wi'thYlQparts byy `.Weightof calciuniethylate; (for-.caloiumiiiethy-.

lli

`purilied as described in Example l.

quence of the formation of the mentholateof earth alkaline metals is ledaway from the vessel.. The heating at the indicated temperature is`continued for about 24 hours; g After this time the mixture isVdistilled by means of steam and the 'distillate is condensed. Une

may separate, for instance by decantation, the condensed menthols fromthe Water. The distillate is a mixture of the several inactivementhols,including inactive menthol, which may be separated by meansoffreezing out or by fractional distillation or by bothv opera` tionswhich may be carried outfinfthe inanner described by the cited copendingapplications; The isolated inactive menthol may be purified according tothe method described in the copending application `146,564 tiledNovember th, 1926.

The isomers `of inactive menthol separated from the latter may be heatedagain with new portionsr ofV the mentholates of earth alkaline metals. 1One may add 50 parts by weight of inactive liquid mentholsmixtureobtained for instance by 'hydrogenating thymoll withrhyd-rogenating catalysts under pressureafter inactive menthol havingbeen separated by any of the methods described in the citedlco# pending`app'lications-eto the isomers of inactive menthol obtained by thepresent process and separated from inactive menthol, andrheat themixture' thus obtained again with l0 parts by weight of calciumethylate(or-another alcoholate ror an alcoholate of another earth alkaline metalindicated above) i 'Emma-Mc 2,-100 parts by weight of inac-l tive.neomenthol,,melting point 5l 52 degrees centigrade'and lOparts byWeight of ethylate of aluminium (oi-:another alcoholate br an alcoholateof another earth alkaline scribed in Example l. rlhe menthols :areisolated by distillation in vacuo.I From the distillate the inactivementhol is isolated and The residue of mentholate remaining after thedis tillation of the menthols may/...be used for Vtreatingfurtheramounts of the isomersof inactive menthol.

Ewample 3.- parts by weigv ol` .cal-V ciumethylate (or anotheralcoholatef oran alcoholate of another ear-thallia me metal indicatedabove) are heated with parts by weight of inactive menthol (or inactiveneomenthol or inactive neoisomenthol) to above l0() degrees centigradeand the formed alco- {holiis distilledoll'. Then l0() parts by weightofrinactive neomenthol, isomenthol or neoed to about 180 degreescentigrade for 24 hours. The product is treated as in Example l.

Example 4.-100 parts by weight of solid, inactive'isomenthol, meltingpoint about 53 degrees centigrade, are mixed with 1.5 parts by Weight ofactivated aluminium (obtained by allowing to act on aluminium smallamounts of caustic soda'lye and hydrargyrumbichloride kor Yhydrartvqyrumbichloride and iodine) and heated to about 18() degreescentigradefor about 40 hours, after the aluminium has been completelydissolved, which is recognizable by the evolution of hydrogenhaving-ceased. 'lhe further treatment may be that of Example l or 2.

Eamnplc 5.-100 parts by weight of inactive'neome-nthol, melting point51159, degrecs centigrade and 100 parts by weight of inactiveneoisomenthol, melting point 12-14 degrees centigradeand 100 partsbyweight of solid Vinactive isomenthol, melting point Vabout degreescentigrade are mixed with 30 parts by weight of calciumethylatefwranother alcoholate or an alcoholate of another alkaline earth-metalindicated above) and heated for about QO-fhours toabout E200 earthalkaline metals to react with the isomers of inactive menthol atiatempera ture vabove j 3; The" process' of manufacturing inactivementhol, the'racemate of lnatural menthoh which consists incausinglinentholates of the Yalkalinefearth metals to react with theisomers :metal indica-ted above) are heated as de- Y 'of linactivel:menthol at temperatures above 100o C; for aperiod offlOto'tO-hours and'ico llD

then separating theformed inactivermenthol from the" reaction productobtained.

4, The process of manufacturing inactive menthol,I which consistsincausing mentholates of the alkaline earth lvmetals -to react with 'the'isomers of inactive'menthol at temperatures labovelO()O C; for a periodof l0 to 40 hours, separating the formed inactive menthol from thecrudereaction product and lcausingthe said reaction productseparated from theinactive4 menthol, to react with fresh portions of'mentholates of thealkaline earth metals. .Y Y l The process Vof manufacturing inactiveAmenthol which consists in reacting on men- `tholates ofthe alkalineearth metals ywith the isomers of inactive menthol attemperatures`1,773,5oo l aboife 1000G, for akperiod of 10 to 40 hours, separa-tingthe formed inactive mentholfrom y the mass produced, ladding tothesaid-,re-v( action product freshportions 'of the isomers ates ofthe'alkaline earth metals. Y

of inactive menthol and causing the said iniX-Y Y ture to react Wthreshportionsof ln'enthol- In `testimony whereof-Vive hereunto affix oursignatures. v C KARL SCHOLLKOPF;y

` ARTHUR SER-INI.

